This study presents experimental results on Photovoltaic-thermal (PVT) solar systems, the commercial photovoltaic (PV) panels used as solar absorbers in PVT collectors, which are amorphous and multi-crystalline silicon. Testing was done with outdoor experiments in the climate of Bangkok corresponding to energy consumption behavior of medium size Thai families. The experimental results show that the thermal recovery of amorphous silicon PVT collector is almost the same as that of multi-crystalline silicon PVT collectors while electricity generation of multi crystalline silicon PVT is 1.2 times as much as that of amorphous silicon PVT. The maximum of heat gain from the PVT systems were obtained in March in summer. It was found that PVT collectors of unit area annually produced 1.1 × 10³ kWh/m² .year of heat and 55–83 kWh/m².year of electricity, respectively. The results show that annual average solar factor of hot water supply is 0.45 for unit collector area. Economical evaluation based on energy costs in Thailand was conducted, which estimated the payback time would be 7 and 14 years for a-Si PVT and mc-Si PV, respectively.

In this study, we estimated the energy saving performance of Photovoltaic Thermal Hybrid System (PVT system) by the computer simulation. PVT system is a device that combines solar thermal collector and photovoltaic cell. We inputted 12 houses data into our simulation. These data are actual general houses data in a year. This simulation results show that electrical efficiency and thermal efficiency of PVT system depend by water flow. PVT system has three type of PV which are crystalline, multicrystalline and amorphous silicon. The efficiency of PVT system of crystalline silicon is higher than the others. Rate of primary energy reduction of PVT system is better than that of PV cell, solar water heater or PV cell (3m^2) + solar water heater (3m^2). Therefore PVT system has the better performance of energy saving.